A conventional steam iron generally includes a housing, an electrothermal plate mounted below the housing, and a water reservoir mounted in the housing. The electrothermal plate includes a plate body that is formed with a plurality of through holes, and a heating member that is mounted in the plate body. The heating member can heat the plate body, so that water is heated and turns into steam via contact with the heated plate body when flowing from the water reservoir to the heated plate body. The steam then exits the steam iron via the through holes in the plate body and cooperates with the heated plate body to remove creases in clothing during the ironing process.
When in use, the plate body reaches a temperature ranging between 200° C. and 220° C., such heat being prone to damage the clothing. In view of this, some manufacturers of steam irons add a bottom plate beneath the plate body with a space therebetween. The bottom plate is formed with a plurality of outlet holes. When in use, the steam enters the space through the through holes and is subsequently discharged through the outlet holes. Damage to the clothing otherwise caused by the high temperature is reducible through the cooperation between the bottom plate with a lower temperature and the steam.
However, with this two-layer structure of the plate body and the bottom plate, contact with the bottom plate with the lower temperature may turn the steam within the space into water droplets, and remain on the bottom plate. This tends to cause the bottom plate to get rusty and shorten the service life of the conventional steam iron.